Effects of Sc and Zr microalloying additions on the microstructure and mechanical properties of new Al–Zn–Mg alloys

“…It was confirmed that Sc addition can significantly improve strength and SCC resistance of 7xxx series alloys [16][17][18][19][20][21][22]. For example, Kannan et al [17] reported the addition of Sc into 7010 Al alloys could introduce a large number of nanosized Al 3 (Sc, Zr) phases to strengthen the alloy and inhibit recrystallization, at the same time, SCC susceptibility of the alloy in neutral 3.5% NaCl solution was reduced.…”

Section: Introductionmentioning

confidence: 91%

Influence of Scandium Addition on Stress Corrosion Cracking Susceptibility of Al-Zn-Mg Alloy in Different Corrosive Environments

Jiang

Yan

et al. 2018

Metals

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Stress corrosion cracking (SCC) susceptibilities of Al-Zn-Mg alloys without and with Scandium addition were evaluated in 3.5% NaCl solution at different pH and different strain rate, using slow strain rate test technique. The results indicate that Sc addition reduces grain size and width of precipitation free zones, and transforms grain boundary precipitates from continuous distribution into interrupted distribution by inhibiting recrystallization. In solution at pH 1, pH 3 and pH 7, Sc addition reduces the degree of localized corrosion of alloy surface and SCC susceptibility of Al-Zn-Mg alloy. However, in solution at pH 10 and pH 12, grain refinement significantly promotes the diffusion of hydrogen atoms into matrix, thus Sc addition increases SCC susceptibility of Al-Zn-Mg alloy. Under different strain rate conditions, Sc addition can all reduce SCC susceptibility of Al-Zn-Mg alloy in solution at pH 1, pH 3 and pH 7, and can all increase SCC susceptibility of Al-Zn-Mg alloy in solution at pH 10 and pH 12. As a result, Sc modified Al-Zn-Mg alloy in practical applications should be avoided in alkaline environments.

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“…In addition, high Zn (8.20 wt.%) and high Sc (0.87 wt.%) content of Al-Zn-Mg alloys in connection with FSP (with optimum process parameters) may result in improved mechanical properties, which is need to be explored. 1) The maximum ageing hardness (~370 HV) of the Al-Zn-Mg alloy (Alloy-1 in Fig. 4) is believed to enhance mainly from the presence of the fine dispersion of ή particles, which are most probably coherent in the matrix.…”

Section: Conclusion and Future Trendsmentioning

confidence: 99%

“…Scandium (Sc) used for grain refinement agent in cast aluminium alloys [1]- [3]. The main functions of these alloys are to increase strength without affecting other properties.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Microstructure And Mechanical Properties of Al-Zn-Mg and Al-Zn-Mg-Sc Alloys After Double Passes Friction Stir Processing

Mandal¹

2017

IJMSE

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Abstract:In this study, the two types of aluminium alloys namely Al-Zn-Mg and Al-Zn-Mg-Sc were developed by casting route. The cast plates were subjected to double passes friction stir processing (FSP) by in-situ vertically fitted milling machine. The tool design and process parameters were found to affect the microstructural and mechanical properties of these aluminium alloys. Therefore, the experimental samples were collected from the stirring zone and selected for mechanical testing. The FSP caused intense plastic deformation, material mixing, and thermal exposure, resulting in significant microstructural refinement, densification, and homogeneity of processed zone. It has been observed that the mechanical properties improved as a result of the complex interactions due to FSP, thermo-mechanical effects, dissolution, coarsening and re-precipitation of the strengthening precipitates in these two experimental aluminium alloys. It can be concluded that the strengthening effect of the Al-Zn-Mg and Al-Zn-Mg-Sc alloys after FSP are associated with the fine grain strengthening, subgrain strengthening and precipitation strengthening of Al3Sc and MgZn2 precipitates. Finally, the resultant properties have been evaluated by FSP parameters such as rotational speed of 1000 rpm and traverse speed of 70 mm/min and specified tool design. In addition, the detrimental effect of high Zn content (~8.20 wt.%) and high Sc content (~0.87 wt.%) aluminium alloy may be attributed to the vaporization of Zn at the time of the FSP. The experimental samples were collected from double passes FSPed zone and critically examined for optical microscopy (OM), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Vicker's hardness testing, tensile testing and fractographic analysis.

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Effects of Sc and Zr microalloying additions on the microstructure and mechanical properties of new Al–Zn–Mg alloys

Cited by 145 publications

References 37 publications

Stress corrosion cracking of a high-strength friction-stir-welded joint of an Al–Zn–Mg–Zr alloy containing 0.25 wt.% Sc

Stress corrosion cracking of a high-strength friction-stir-welded joint of an Al–Zn–Mg–Zr alloy containing 0.25 wt.% Sc

Influence of Scandium Addition on Stress Corrosion Cracking Susceptibility of Al-Zn-Mg Alloy in Different Corrosive Environments

Investigation of Microstructure And Mechanical Properties of Al-Zn-Mg and Al-Zn-Mg-Sc Alloys After Double Passes Friction Stir Processing

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